Selecting Quality Trees from the Nursery

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Urban Forest Hurricane Recovery Program
http//treesandhurricanes.ifas.ufl.edu
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Selecting Quality Trees from the Nursery
Dr. Edward F. Gilman and Traci Partin
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Poor vs. good quality
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Advantages to selecting quality trees

• Higher survival post-planting
• Greater longevity in the landscape
• Reduces period of time needed for establishment
• Reduces likelihood of failure from structural
  defects during a hurricane

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Important considerations for selection

• Production method
• Maximum size at planting
• Root ball dimensions
• Root collar location
• Root defects
• Root ball caliper height relationship
• Trunk and branch structure
• Other

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Tree production methods

• Balled in burlap (BB)- root pruned prior to
  transplanting- not root pruned

• Container- above ground- pot in pot- fabric
• Bare root

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Choose among tree production methods based on
weight and staking capabilities
BB Balled-in-burlap
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Tree survival in the landscape can depend on the
production method and irrigation practices after
planting
BB Balled-in-burlap
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Tree survival in the landscape can depend on the
production method and irrigation practices after
planting
BB Balled-in-burlap
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Here is the summary story

• Under limited irrigation
• Root pruned, hardened-off BB last to die
• Containers in the middle
• Recently dug BB first to die
• Under appropriate, intensive irrigation
• It does not appear to matter

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Oak not root pruned
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Root pruned last production year only
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Root pruned last year and year before
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Not root pruned
One year after transplanting
Root pruned last production year
Root pruned last 2 production years
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Conclusions about root pruning

• Root pruning during production provides a product
  that
• 1) is slightly smaller
• 2) has a denser, more fibrous root
  system
• 3) has a more uniform root system
• 4) transplants more successfully

Note Not all species require root pruning. Some
have a dense fibrous root system without root
pruning.
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Important considerations for selection

• Production method
• Maximum size at planting
• Root ball dimensions
• Root collar location
• Root defects
• Root ball caliper height relationship
• Trunk and branch structure
• Other

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Selecting the right tree size

• Irrigation capabilities
• When irrigation is limited
• Site drainage
• If drainage is poor
• Weed control and mulch management
• If weeds are not controlled and compete with
  tree for water

then select small nursery stock such as 1.5 to 3
inch caliper trees.
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Tree size impacts tree establishment rate
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Tree size impacts tree establishment rate
Percent caliper, height, and spread increase
between May and October 2005 for live oak
transplanted from 15 and 45 containers to the
field. ___________________________________________
_____ Container caliper height
spread Size increase increase
increase -----------------------------------------
-------------------------------- 15 (1 caliper)
60.4a 36.5a
55.8a1 45 (2.5 caliper)
14.8b 9.1 36.4b
________________________________________________
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Conclusions about tree size

• Smaller trees take less time and water to
  establish.
• Survival of smaller nursery stock is greater if
  irrigation capabilities are limited.
• Growth rate of small trees is significantly
  greater than when the same species is planted at
  a larger size.
• Unless plenty of water can be supplied, it is
  better to plant smaller trees.

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Important considerations for selection

• Production method
• Maximum size at planting
• Root ball dimensions
• Root collar location
• Root defects
• Root ball caliper height relationship
• Trunk and branch structure
• Other

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Root ball dimensions

• Root balls of any shape perform equally well in
  well-drained soil.
• Tall root balls help keep deeper roots moist.
• Wide and shallow root balls are better suited for
  planting in poorly-drained and compacted sites.
• Shallow root balls dry quicker on well-drained
  sites.

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Good for poorly drained site
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Important considerations for selection

• Production method
• Maximum size at planting
• Root ball dimensions
• Root collar location
• Root defects
• Root ball caliper height relationship
• Trunk and branch structure
• Other

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Root collar location

• Remove soil or media around the base of the trunk
  until you locate the top-most root.

Root flare
Top most root

• The top-most major root should be within 2-3 of
  the surface of the root ball.

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Nicely positioned root collar
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Trunk without flare should trigger a root check
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Planted too deeply
Soil level
Roots generated after planting
Most common
Original top root
Less common
No roots generated after planting
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Conclusions about trees planted too deep

• Do not purchase the tree.
• Soil, media, and roots growing above the original
  top-most root should be mostly removed prior to
  planting.

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Important considerations for selection

• Production method
• Maximum size at planting
• Root ball dimensions
• Root collar location
• Root defects
• Root ball caliper height relationship
• Trunk and branch structure
• Other

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Types of root defects

• Circling roots
• Kinked roots
• Girdling roots
• Root-bound

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Circling roots
Notice roots circling at the top and sides of the
root ball.
Circling roots develop when trees are grown in
containers for a prolonged period, causing roots
to be deflected by the container wall and to
circle the outside of the root ball.
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This tree was found leaning after a hurricane.
The cause circling roots
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Kinked roots
Kinked roots occur if roots are folded into a
propagation bed at the seedling stage.
Kinked root
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Girdling root

• Girdling roots are formed when regenerated roots
  grow perpendicular to a cut root, or from growing
  in a container too long.
• As the tree grows, these roots may meet the trunk
  and begin to strangle it.

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Girdling root brings down a giant
Indented trunk
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Root-bound
Root-bound trees have many roots circling around
the outside of the root ball. This causes a
physical barrier, preventing the tree from
spreading roots into the landscape soil after
planting.
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Many roots inside but few on the edge of root
ball indicate quality.
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Quick test for root quality
Good Quality
Poor Quality
Trunk does not bend
Trunk bends
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Conclusions about root defects

• Root defects have a significant impact on tree
  performance in the landscape.
• Defects can occur on all trees regardless of the
  production method.
• Problems are easier to correct in the nursery
  when the tree is young some correction can occur
  at the time of planting.

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Important considerations for selection

• Production method
• Maximum size at planting
• Root ball dimensions
• Root collar location
• Root defects
• Root ball caliper height relationship
• Trunk and branch structure
• Other

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Root ball standards
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Way over-grown
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Conclusions about root height ratio

• Ideally, the dimensions of the root ball should
  exceed the minimum that is recommended.

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Important considerations for selection

• Production method
• Maximum size at planting
• Root ball dimensions
• Root collar location
• Root defects
• Root ball caliper height relationship
• Trunk and branch structure
• Other

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Trunk structure

• Shade trees of lesser quality have two or more
  trunks
• Best quality shade trees have one dominant trunk

poor quality
best quality
good quality
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Brancharrangement
Good quality
Poor quality

• Major branches and trunks should not touch.
• Branches should be less than 2/3 trunk diameter.
• Main branches on shade trees should be spaced
  apart.

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Young quality tree

• Small temporary branches are OK
• Lower branches help the root system and lower
  trunk grow
• Protects trunk by forming a barrier to mechanical
  injury.

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Poor quality

• Codominant stems
• Major branches/ trunks touching
• V-shaped crotch
• Included bark

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Conclusions about structure

• Choose trees that have been trained in the
  nursery to have good structure.
• Trees with good form at time of planting will
  need maintenance to keep one dominant trunk.
• Trees with poor structure will need more severe
  and time-consuming pruning visits.

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Important considerations for selection

• Production method
• Maximum size at planting
• Root ball dimensions
• Root collar location
• Root defects
• Root ball caliper height relationship
• Trunk and branch structure
• Other

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Other factors influencing tree quality

• Trunk injury or broken branches.
• Tree wrap (may be covering up wounds).
• Disease or insect damage.
• Canopy uniformity and fullness.
• Quality of old pruning cuts.
• Seed or propagule source.
• Foliage color and size.
• Presence of stakes.

Trunk injury
Tree wrap
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• Carefully inspect the tree for disease or insect
  damage.

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Canopy uniformity and fullness
Good uniformity and fullness
Poor uniformity and fullness
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Quality of old pruning cuts
Flush cut
Good cut
Callus forming only around sides of flush cut.
Branch collar no longer present.
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Seed or propagule source
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Foliage color and size
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Presence of stakes
Stake
Stake
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Example of a good quality tree

• One dominant trunk
• Branches spaced evenly
• Canopy full and uniform

Visit the website Trees and Hurricanes http//tr
eesandhurricanes.ifas.ufl.edu